The case of a Columbia professor's alleged affair with his adult daughter has people questioning laws of consent, culpability...and the incest taboo.

The case, in which the 46-year-old David Epstein maintained a relationship with the 24-year-old over the course of several years, brings up a confusing mish-mash of questions, both moral and legal. Law professor Eugene Volokh outlined them comprehensively here:

(1) Should it be illegal, and, if so, exactly why? Is it just because it's immoral? Because legalizing incest would, by making a future sexual relationship more speakable and legitimate, potentially affect the family relationship even while the child is underage (the view to which I tentatively incline)? Because it involves a heightened risk of birth defects (a view I'm skeptical about, given that we don't criminalize sex by carriers of genes that make serious hereditary disease much more likely than incest does)?

After all, the relationship in this case allegedly began after Epstein's daughter reached the age of consent. It isn't a clear-cut case of child abuse, and there are no allegations that the three-year-long relationship carried on without the daughter's consent.

While laws vary from state to state (both parties were charged in a Florida case) the taboo against incest remains universal, and the reason, as articulated by one legal expert, is compelling:

Regardless of the age of the child, there's still a theory that a parent is always a parent, a child is always a child and, as a result, there truly can't be a consensual sexual act...The idea is the perpetrator is the parent and the victim is the child. We don't normally prosecute a person falling within the protected class, and you remain a member of the protected class even above age of consent.

In case you're wondering how Lawrence v Texas, the landmark 2003 decision that basically told the court to stay out of adults' bedrooms, figures in? Incest is generally regarded as an exception because there's the added issue of "an enhanced possibilit­y of genetic mutation of a possible offspring." Not to mention the unspoken possibility of "grooming" children for adult incestuous relationships, horrible though the thought may be.